I've written before about the gross grey fuzzy matter that attacks the leaves of our beloved cannabis plants known as mold. By now I'm sure you have become an expert at checking your leaves and wiping them down with with a mixture of apple cider vinegar at the first sign of a spore.

Botrytis Cinerea

Unfortunately, there is another mold that can just as easily creep up on your plant and start killing it. It's bud rot and it's no joke. This mold also goes by Botrytis Cinerea or during another of its life cycle it's called Botryotinia Fuckeliana, although the latter name is more fitting for this fungus.

Unpleasant surprise

Bud rot commonly attacks marijuana plants first from the inside of thick buds just a couple weeks before harvest. So, in fact, a nice big bud could give you an unpleasant surprise and be "hollow" due to mold damage.


The first sign that you may notice if your plant has bud rot is when one of the leaves sticking out of the kola is withering and drying out. To further investigate you should bend open the bud to see the inside of it and the stem. You know you're doomed when you see white or gray hairy mold. These hairy threads are called mycelia. Mycelium absorbs nutrients from the host. This is done by releasing enzymes that break down the cannabis plant matter into a nutrient slime that the Botrytis Cinerea can absorb.

Inspect your buds

In very humid conditions the whole bud will become slimy, or in very dry climates the affected parts of the bud will easily crumble. Even dried and stored marijuana is not entirely safe from this mold, so you should inspect your buds from time to time. An outbreak can spread to all of your plants and quickly destroy them within a week.

Genetic varieties

Throughout the winter months many genetic varieties of Botrytis Cinerea endure throughout the cold in the form of different mold species. When spring arrives the various mold species produce conidiophores that produce millions of asexual spores and spread around by means of wind or rain.

They are everywhere

You can't really avoid mold spores; they are everywhere. By the time you've finished reading this blog post you've inhaled some kind of spore or another. That's why it's so important to take the necessary precautions to lower your risk of a Botrytis Cinerea infestation.

Avoid contamination

This mold flourishes in cool, contaminated environments that have humid air and poor circulations. Outdoor growers should be cautious with weather conditions close to harvest time. Morning dew, frost, rain, and cool evenings can all raise the risk of mold. Cleanliness and climate control measures can help you to avoid contamination.

Remove all fabric

When growing indoors, remove all fabric in the grow room like carpets and fabric curtains as these things are usual culprits that harbor botrytis spores. It's also a good idea to wash the room with a bleach and water solution. Forget about covering the floors with plastic or hanging some up on the walls as this can trap moisture. Also, don't forget to take out the trash. Just as important as it is to remove dead foliage, it's also important to take it out of your grow room so that it doesn't rot and spread mold. Fans in a grow room are always a good idea.


The temperature in your grow room should be higher than 70 degrees Fahrenheit (21 degrees Celsius), and the humidity should be under 50%. If you're growing outdoors you have to rely on other ways to decrease the chance of spreading mold. For instance, you can spread thick plants with netting or twin to increase airflow. Removing interior and weak branches will help with the circulation.

Take action

If you do have an outbreak of bud rot then you must take action right away. Sterilize your pruning shears with alcohol or hydrogen peroxide and cut the infected bud from an inch under the damaged area. Try not to spread the spores while doing this, and don't touch another plant before cleaning your hands and equipment. Dispose of the moldy buds in a plastic bag that can be closed and take it far away from your grow area.

Copper spray

If you've had problems with bud rot in the past or you want to be extra careful about it then a copper spray is an option for you. It can be sprayed onto your plants every week until harvest.

Check your plants regularly

Bud rot is a nasty thing to combat. Since it devastates the prized part of your plant it's just that much worse to deal with. As long as you take the necessary precautions and check your plants regularly you stand good chance to avoid it altogether.

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